The present invention relates to an arrangement for arresting a movable member.
More particularly, the present invention relates to an arrangement for arresting a seat of a vehicle.
It is known in the motor vehicle art to arrange a safety belt directly on a seat of a vehicle. In this case the position of the safety belt depends on the position of the seat. Therefore, it is essential to ensure reliable arresting of the seat in any of its positions, especially in case of an accident where the requirements as to the arresting of the seat in its position and as to the operating reliability of an arrangement for arresting the seat, are put to a severe test.
It is also known in the art to provide both sliding elements of the movable seat with a separate member for arresting the seat in a desired position. Usually both such arresting members are actuated by a single manual lever. There might, however, be a situation where due to either assembly inaccuracies or distortion (e.g., twisting) of the seat, only one of the arresting members actually engages with a cooperating fixed element whereas the other one does not. If this is the case, the non-engaged arresting member merely abuts against the cooperating fixed member without actually engaging the latter. If an accident occurs under these circumstances, the seat of the vehicle is fixed in its position only by one of two arresting elements, the one which has properly engaged the corresponding fixed member. Obviously, such a situation can result in very undesirable consequences.
During an accident, the seat of the vehicle is subject to considerable acceleration relative to the chassis of the vehicle, if the seat is not reliably fixed to the base of the vehicle against such relative movement. For example, when a head-on collision at the speed equal to 50 km/h occurs, an acceleration equal to about twenty times gravity is observed, i.e., on the magnitude of approximately 200 m/sec.sup.2. Under such magnitudes of acceleration, the speed of movement of the fixed seat guide rails of the chassis and the sliding rails of the seat relative to one another increases considerably within a very short time. The known arresting arrangements are not of such construction as to permit, under such conditions, the arresting member which is not in engagement with the fixed element, to become engaged therewith sufficiently to stop the movement of the seat relative to the chassis.